Electric furnace.



J. W. BROWN.

ELECTRIC FURNACE.

APPLICATION FILED APR.22. 1914.

Patented July 27, 1915.

I N VEN TOR.

V. N w Wm UMM H w av W N H D J WITNESSES.-

snares PATENT JOHN V7. BROWN, 0F LAKEWODD, OHIQ, ASSIGNOR T0 NATIONALCARBON COMPANY, 0F CLEVELAND, OHIQ, A CORPORATION OF NEW JERSEY.

ELECTRIC FURNACE.

Specification of Letters Patent.

Original application filed January 8, 1912, Serial No. 670,071. Dividedand this application filed April 22,

T 0 all whom it may concern:

Be it known that 1, JOHN W. BROWN, a citizen of the United States,residing at Lakewood, in the county of Cuyahoga and State of Ohio, haveinvented a certain new and useful Improvement in Electric Furnaces, ofwhich the following is a full, clear,

and exact description.

This application is a division of my ap plication, Serial No. 670,071filed January 8th. 1912. v

The improvement relates to electric furnaces and more specifically tothat type in which the charge is a conductor of electricity andiscontinually fed through the furnace.

llt is particularly adapted to the manufacture of graphite, and to thebaking and calcining of cokes and .other carbonaceous materials. In theelectric furnaces as usually constructed, there is a large waste of heatdue in part to the imperfect heat insulating medium of which the body ofthe furnace is constructed and to the large amount of heat contained inthe treated charge when it leaves the heatirnc zone.

ln order to continuously move the charge through the furnace it hasheretofore been foundnecessary to cool it to the temperature that wouldadmit of its being conveyed out into the open air without injury to thetreated product. The cooling has been done by forcing water throughpipes in the lower part of the furnace, or by passing them through thetreated charge itself. The heat absorbed by the water is all wasted andone of the objects of my invention is to utilize this heat.

Another object is to do away with the necessity for continual supply ofcold water which is an expensiveand wasteful method.

Another object of my invention is to preheat the charge so that it willnot be neces sary to use so much electric energy.

Another object is to treat continuously relatively small quantities ofthe charge to a high temperature for a relatively short period of time.

Further objects will appear in the description of my invention,particular reference being had to the drawings in which:

Figure 1 is a central cross sectional view of a continuous furnace inwhich the charge is preheated by passing a heat absorbing Serial No.333,640.

gas through the treated material. Fig. 2 is a detail of a pair of carbonbricks used in the furnace of Fig. 1.

Referring to Fig. 1, 10 represents the outer inclosing walls of theheating zone of the furnace, and is made of some heat in sulatingmaterial which is a non-conductor of electricity. llhe lower walls arelined with a carbon-section 11 in the shape of a. hollow upright frustumof a cone. A hollow cylindrical section 12 built up of corrugated orgrooved carbon blocks such as shown in Fig. 2 rests on the top of themember 11 and has its opening in coincidence with the upper opening ofthe core. Upon the hollow cylindrical section 12 is placed an invertedfrustum 13 similar to the section 11. but preferably made of aninsulating material the same as that of the furnace walls. In thismanner an upper and a lower chamber 13' and 11 respectively are providedwith a narrow intermediate chamber 12'.

.a lower electrode 14 having a terminal 1(3 is placed beneath and incontact with the lower conducting section 11. Upper electrode H and itsterminal 15 are similarly placed on top of the member 13.

With the construction thus disclosed, the current will flow from theupper electrode 1 through the upper part of the charge until the builtup section 12 is reached. Here the greater part of the current will passdown through the constricted portion of the charge which is surroundedby the section and a small part of it will flow through the section 12.\Vhen the section 11 is reached the current will again divide, most ofit flowing through the carbon section 11 directly to the ,lowerelectrode 14-. A small part of the current, however, will flow throughthe lower part of the charge to the lower electrode. The corrugatedsurface of the sections 12 increases the resistance to such an extentthat only a small part of the current passes therethrough. This highresistance is easily obtained by placing the grooves of one blocktransverse to those of the adjacent block, thereby securing a number ofpoint contacts of high resistance. However. the carbon blocks will beheated somewhat by the current passing therethrough and will aid inheating material in the constricted portion of the charge. it will thusbe seen that the. charge tit) another screw conveyer 18.

in the chamber 12' surrounded by the built up section 12 can be quicklyheated to a very high temperature. The charge, consisting usually ofgranular coke, is fed into the top of the furnace by the screw conveyerl7 and removed from the bottom of The rate of charging and dischargingthe material being treated depends primarily upon the temperature towhich the charge in the constricted opening is to be heated, althoughthis may also be controlled to a certain extent by adjusting thecurrent.

The fan 19 forces an inert gas into the bottom of the furnace andwithdraws it from the. top. The gas 1n passing through the heated chargein the chamber 11 cools it so that it may be removed into the air bymeans of the conveyer 18. The hot gas which has been previously heatedby passing through the treated charge and through theconstricted-portion delivers up its heat to the untreated charge in thechamber 13 and in this manner preheats it. The furnace shown rial, meansto provide a constricted opening in the drawing is greatly reduced inheight as compared with its width, but this is for the purpose ofillustration. In practice the furnace would be 20 or 30 feet high andthe space above and below the heating zone would be great enough for thegases to absorb the heat from the charge in the lower part of thefurnace and deliver substantially all of it to the charge in the upperpart of the furnace so that it will emerge therefrom in a substantiallycool state. A valve 20 is also provided for regulating the supply of gaswhich is to be forced through the charge.

Having described my invention, what I claim is: I

1. In an electric furnace for treating granular material, inclosingwalls, positiveand negative electrodes spaced apart in the direction ofmovement of the material, chambers for the treated and untreatedmaterial having a constricted opening therebetween adapted to be filledwith material being treated.

2. In an electric furnace for treating granular material, an upperelectrode, a chamber above said upper electrode, a lower electrodespaced from said upper electrode in the direction of movement of thematerial,

a chamber below the lower electrode and means to provide a constrictedarea between said chambers whereby an electric current passes betweenthe electrodes and through the material in the constricted area.

3. In an electric furnace for treating granular material, an upperelectrode, a chambe' above said upper electrode, a lower means toprovide a constricted area between said chambers whereby an electriccurrent passes through the electrodes, and through the material in theconstricted area, and means for admitting and removing the material atthe predetermined rate.

4. In an electric furnace for treating granular material, positive andnegative electrodes spaced apart in the direction of movement of thematerial, means to provide a constricted area between said electrodeswhereby an electric current passes through the material in theconstricted area to strongly heat it, and means for removing the heatfrom the treated charge and delivering it to the untreated charge.

5. In an electric furnace for treating carbonaceous material, a chamberfor untreated material, and a second chamber for the treated material.electrodes situated in each of the chambers adapted to heat thematebetween said chan'ibers. means for admitting and removing thetreated material at a predetermined rate, and means for cooling thetreated material whereby the untreated material is preheated.

6. In an electric furnace for treating granular material, inc/losingwalls, positive and negative electrodes, chambers for the treated anduntreated material having a constricted intervening space therebetweenadapted to be filled with thematerial being treated and to be heated bythe passage of current therethrough, and means for forcing a fluidwithin the walls of said chambers containing the treated materialwhereby heat is absorbed from said treated material, and delivered tothe untreated material.

7. An apparatus for preparing granular carbon, consisting of an upperand a lower chamber a relatively narrow throat connecting said chambers;means to cause an electric current to pass through the material in saidthroat when in operation, an exit for the prepared carbon at the lowerpart of the lower chamber, whereby the exit of the prepared carbontherefrom may be controlled to control the movement of carbon particlesthrough the throat in the path of the elec trical current.

In testimony whereof, I hereunto aifix my signature in the presence ofwitnesses.

JOHN IV. BROIVN.

IVitnesses:

Ina J. ADAMS, H. G. Gnovnn.

